Bacterial spot
Symptoms
Manifests as dark spots with a raised center on leaves and stems, later the leaves begin to yellow. Dark, growing spots may appear on the fruits. Cool, humid weather and splashing water droplets allow the disease to spread rapidly.
Control and prevention
Can be sprayed with 0.3% copper oxychloride; it will not cure, but will strengthen the plant and limit bacterial activity.
Related problems
Similar symptoms might indicate a different cause — compare them.
Bacterial canker
Quite rare, but if it attacks, it can destroy the entire season's harvest. The main symptoms are wilting, curling, and browning of leaves. Initially, not the entire leaf wilts, only a part of it. Even if the plant is infected at the seed stage, symptoms may not appear until flowering. Later, spots with a double border appear on the fruits. The disease spreads rapidly — infected plants must be removed immediately.
Early blight and black fruit rot
Alternaria solani
Usually appears when fruits begin to set. First affects the lower leaves, then the stem and fruits. Large brown or black spots with concentric rings appear on them. Around the spot, the leaf begins to yellow and dies. It also attacks potatoes and eggplants. The fungus is resistant and persists for several years.
Mold
Symptoms caused by various fungi. Mold only survives in high humidity.